Madness Below

You star off choosing one of two protagonists.

Alexandrius Kalimor, a paladin and a prince of the kingdom Kalim where the story takes place. He choose to take this mission as a part of proving himself worthy to the throne.

Evelynn, a mercenary hired to investigate missing villagers. Evelynn was shunned by her family in the past due to her transgender status and had a hard life. But she is a skilled warrior and thus manage to survive through taking difficult missions.

It starts off as a fairly straight forward mission. Find the missing soldiers and villagers. Find out what happened. But it turns out things aren't that simple. Just being near that cursed dungeon messes with your head. Weakens your grip on reality and more prone to listen to the darker parts of your soul. Thus the rabbit hole goes deep indeed.